Gliederung

Objective: In non-synostotic plagiocephaly overlapping of the bony plates and the so called ‘sticky suture' is still of controversy and is believed to express a pathological fusion process. Complemental synchrotron-microtomographic (SRmCT) studies were undertaken to enlighten the question, if positioning head deformities can be assumed as a true suture pathology.

Methods: Six pathological sutures including sagittal synostosis and non-synostostic plagiocephaly (NSP), were compared to a group of normal sutures (n=6) by histological and SRmCT studies. SRmCT is a special synchrotron radiation source with a high photon flux providing a monochromatic X-ray beam with a very high spatial resolution. Morphological characteristics of the different suture types were evaluated and bone density alongside the sutures measured to compare the osseous structure of the adjacent bony plates of normal and pathological sutures.

Results: SRmCT studies showed that 1) sutures and adjacent bones in NSP are comparable to normal sutures regarding to their morphological aspects 2) bone density in the adjacent bony plates of NSP and normal sutures are not different 3) thickening of the diploe with ridging of the bone in sagittal synostosis is associated with significant higher bone density 4) synostotic sutures are only partially fused but vary in their extent and 5) non-fused sections in sagittal synostosis behave like normal sutures without any signs of pathological bone formation.

Conclusions: Sutures in NSP-patients were found without any morphological irregularities or different bony structures alongside the sutures compared to normal sutures. Thus a true suture pathology or osseous changes of the adjacent bony plates is highly unlikely in NSP. Even the number of specimens is limited in this series, fusion of cranial sutures seems to start at one undeterminated point spreading along the suture while other parts of the same suture are not involved according to morphological aspects and bone density measurements of the adjacent bones. This theory represents a dynamic fusion process completing over time but just starting too early.